Translatory potentiometer



Feb. 2, 1954 R. w. SEARLE TRANSLATORY POTENTIOMETER Filed March 9, 1953 irazyk r V M! 1a @222 zri 17 r 3' Y INVENTDR. J 9 44; I

AT ORNEY.

Patented Feb. 2, 1954 TRANSLATORY POTENTIOMETER Raymond W. Searle, Weston, Mass., assignor to Technology Instrument Corporation, Acton,

Mass.

Application March 9, 1953, Serial No. 340,946

7 Claims. 1

The present invention relates to a translatory potentiometer, and more particularly to a translatory potentiometer construction which enables potentiometers to be made in various different lengths and various characteristics with a minnnum of effort.

It is customary in servo-mechanisms to employ potentiometers for control purposes. In some cases the apparatus to be controlled moves with such rapidity and requires such accuracy that a rotary potentiometer is not feasible. For translating into electrical current the mechanical movement, which is a relatively high speed, it, therefore, is desirable to use translatory potentiometers where the wiper element moves linearly. In the use of such linearly actuated potentiometers various different lengths of potentiometers are needed, and various electrical characteristics are required. In some cases it is desirable that for certain portions of the motion of the control rod of the potentiometer other circuits or other factors be controlled. This in the past has necessitated making all such potentiometers to special order, thus resulting in appreciable expense.

It, therefore, would be desirable to provide a translatory potentiometer design which would be more readily adaptable to the construction of potentiometers of different lengths to accommodate different linear motions. It furthermore would be desirable to be able to combine in a single struc ture a plurality of control elements responsive to the linear movement of a control member. It furthermore would be desirable to provide a design for a translatory potentiometer which is sufiiciently versatile in its application to minimize the expense and effort ordinarily required to meet the specifications. In accordance with the present invention these desirable characteristics and others are attained by an improved construction where the translatory potentiometer is formed of a casing having four similar sides, each capable of carrying a resistor element. Suitable end plates are provided for supporting the control rod and contacts and to provide electrical connections to the various resistor elements and, contact rods. With this as a basis, short or long translatory potentiometers with one or a plurality of resistor elements are readily constructed.

It, therefore, is an object of the present invention to provide an improved translatory variable resistor or potentiometer.

Another object of the invention is to provide an 2. improved translatory variable resistor for multiple control functions.

A still further object of the invention is to provide an improved translatory variable resistor construction.

Still another object of the invention is to provide an improved translatory variable resistor or potentiometer construction which is simple and economical to manufacture, and which may be adapted for one or a plurality of resistor elements. Other and further objects of the invention subsequently will become apparent by reference to the following description taken in conjunction with the accompanying drawing wherein:

Figure 1 is a side view of a translatory vari able resistor or potentiometer embodying the present invention having one of its side plates removed;

Figure 2 is a cross-sectional view seen in the direction of the arrows along the line 2-2 of Figure 1;

Figure 3 is a cross-sectional view as seen in the direction of the arrows along the line 3-3 of Figure 1;

Figure 4 is a view similar to Figure 2 showing the embodiment where only a single resistor element is employed; and

Figure 5 is a partial view of one of the side elements as viewed in the direction of the arrows along the line 5-5 of Figure 4.

Referring to the drawing it will be noted that a control rod ii is provided for reciprocable movement in accordance with an element Whose l, motion is to be utilized to provide a change in an electric circuit. The rod l l is carried by a bearing and mounting sleeve [2, which in turn is supported by an end plate IS. The translatory potentiometer has another end plate l4 provided with a plurality of electrical terminals or wires 15 for connection to an electrical circuit. The two end plates 13 and I 4 are connected together by a plurality of similar side members It. Each side member has a longitudinally extending opening I! for receiving suitable fastening cap screws I8. The cap screws l8 pass through the end plates ii and [4 to form a structure which serves as a casing for the translatory potentiometer. On the inner surface immediately above the aperture ii there is provided a ridge member to, which is adapted to fit into a groove 2! at the end of a cooperating side member 16. On the inside surface the side plate H has an under-cut channel 22 so formed as to securely hold in position a strip of insulating material 23 and a. resistor element comprising an insulated support 24 and a wire wound portion 25. At the bottom of the channel 22 there is formed another longitudinal channel 26 which as seen from Figure 2 serves as a space for the return conductor 21 from one end of the resistor Wire 25. This channel 26 as may be seen from Figure 4 in another embodiment serves as a guiding means for the inner end of the rod II. On the inner surface of the side plate Hi there is further provided a longitudinal groove 28 which carries a U-shaped insulator 29 to support a contact bar 3|.

It will be noted from Figure 2 that the top and bottom side members 1'6 are each provided with resistor elements and contact bars. If desired three or all four sides l6 may be provided with resistor elements and contact bars.

The inner end of the rod H is provided with an insulated structure having a cylindrical boss or sleeve member 32 provided with four projecting arms 33. The arm 33 adjacent a side If: carrying a resistor element 25 is provided with a pair of pins 34 extending through the arm 33. One side of the pins 34 is provided with a contact arm or spring 35 which engages the resistor element, While the other ends of the pins 34 are provided with a contact spring 36 which engages the contact bar 3!. The boss 33 may be retained in the end of the rod I l by suitable fastening means such as a set screw 31.

Where only one side element it is to carry a resistor element, the construction of the potentiometer or variable resistor is modified as shown in Figure There one of the arms 33 of the insulated sleeve 32 carries two pins 3% for wiping contacts 35 and 36. Another arm 3-3 displaced 90 from the arm which carries ie two pins S l is provided with a rod or pin 38 which travels in the longitudinal groove or channel formed within the longitudinal channel 22. The pin 33 prevents rotation of the rod ll should there be any inequality in the tension of the respective wiper contacts 35 and 36. Such guide means has not been found necessary where a balanced arrangement such as that shown in Figure 2 is used. It, of course, will be apparent that a pin such as 38 might be used in a translatory potentiometer having three resistor elements.

From the foregoing description it should be apparent to those skilled in the art that the construction readily lends itself to the manufacture of translatory potentiometers which may be short or long as desired. Where but a single resistor element is employed the construction is similar to that shown in Figure l. Where a pin rality of resistors are to be engaged over all or a portion of the longitudinal movement of the wiper contacts, the construction will be in accordance with the teaching illustrated in Figure 2. The dovetailed arrangement forms a rigid structure requiring a minimum of fastening means such as four cap screws 18 at each end. The side members it are preferably made of metal in order to provide the necessary rigidity and strength for the relatively long transiatory potentiometers frequently required. While this may be desirable for such potentiometers, it, of course, will be appreciated that other material might be employed where great lengths are not involved.

While for the purpose of illustrating and describing the present invention certain preferred embodiments have been shown in the drawing, it is to be understood that the invention is not 4 to be limited thereby since such variations are contemplated as may be commensurate with the spirit and scope of the invention set forth in the accompanying claims.

I claim as my invention:

1. A translatory potentiometer casing for supporting therein an elongated resistor strip comprising two square end plates, one of said plates having a bearing member for a reciprocable rod carrying a contact for engaging said resistor strip, four similar side plates having tongue and groove means interconnecting adjacent side and edge portions of said plates, and fastening means passing through the corner portions of said end plates into the ends of each of said side plates.

2. A casing for a variable resistor comprising two square end plates, one of said plates having a bearing member supporting a reciprocable rod, four similar side plates having tongue and groove means interconnecting them, fastening means passing through said end plates into the ends of each one of said side plates, channel means provided on the inner surface of each side plate for supporting a resistor element and a contact bar, and means carried by the inner end of said rod for making contact with the resistor element and the contact bar of a side plate.

3. A casing for a variable resistor comprising two square end plates, one of said plates having a bearing member for supporting a reciprocable rod, four similar side plates having tongue and groove means for interconnecting said plates, fastening means passing through said end plates into the ends of each one of said side plates, channel means provided on the inner surface of each side plate for supporting a resistor element and a contact bar, and insulator means carrying a set of contacts for each side plate having a resistance element and a contact bar, said insulator means being mounted on the inner end of said reciprocable rod whereby said contacts serve to interconnect electrically the contact bar with said resistor element.

4. A casing for a potentiometer comprising two square end plates, one of said plates having a bearing member for supporting a reciprocable rod, four similar side plates having tongue and groove means interconnecting adjacent portions, fastening means passing through said end plates into the ends of each one of said side plates, channel means provided in the inner surface of each side plate for supporting a resistor element and a contact bar, a resistor element and a contact bar mounted in said channel means, and an insulator structure mounted on the inner end of said rod, said structure carrying a set of resilient contacts for each side plate having a resistance element and a contact bar, said contacts serving to interconnect electrically the bar with said resistance element, and a plurality of contacts carried by the other end plate for connection to the resistor elements and conductor bars of each side plate.

5. A casing for a potentiometer comprising two square end plates, one of said plates having a bearing member for a reciprocable rod, four similar metal side plates having tongue and groove means interconnecting adjacent surface portions, and fastening means passing through said end plates into the ends of each one of said side plates, channel means provided on the inner surface of each side plate for supporting an insulated resistor element and an insulated contact bar, a resistor element and a contact bar mounted in certain of said channel means, and contact means carried by the end of said rod for interconnecting a resistor element with the adjacent contact bar of a side plate.

6. A casing for a variable resistor comprising two square end plates, one of said plates having a bearing member for carrying a reciprocable rod, four similar side plates having tongue and groove means interconnecting adjacent side plates, fastening means passing through said end plates into the ends of each one of said side plates, channel means provided on the inner surface of each side plate for supporting a resistor element and a contact bar, a resistor element and a contact bar mounted in one side plate channel means, contact means carried by the inner end of said rod for making contact with the resistor element and the contact bar, and means carried by the inner end of said rod for engaging a channel in one of the other side plates to guide said rod.

7. A potentiometer comprising two square end plates, one of said end plates having a bearing member supporting a reciprocable rod, four similar elongated metal side plates each having a plurality of channels formed in the inner face thereof for supporting a plurality of electrical elements, interlocking tongue and groove means arranged between the edge of one plate and the inner face of the adjacent plate arranged at right angles to the first plate, a plurality of elongated electrical elements mounted within said channels, and insulated electric contact means guided by the end of said reciprocable rod for electrically interconnecting adjacent electric elements. ments.

RAYMOND W. SEARLE.

References Cited in the file of this patent UNITED STATES PATENTS Number 

